Features of design, construction and operation of underground tunnels and tunnel structures in dense urban areas

Abstract

The development of a modern city and the increase of its transport infrastructure, in particular metro facilities, has a significant impact on the urban environment and requires the development and implementation of a set of special protective measures. Moreover, if the construction of metro station complexes is carried out, as a rule, in relatively free areas with minimal impact on the surrounding buildings, then during the construction of tunnels and tunnel structures, engineering communications, buildings and structures located on the earth’s surface, including transport facilities, architectural monuments and cultural heritage objects fall into the zone of their influence. The effectiveness of design solutions for the protection of objects that are in the zone of influence of the construction of underground structures is largely determined by the degree of reliability of the assessment of geotechnical conditions and the results of the survey of the technical condition of building structures. Analysis of the causes of the formation and development of emergency situations and incidents arising in the construction and operation of underground structures shows that they are mainly the result of the use of unreliable initial engineering-geological and hydrogeological conditions, significantly changing due to intensive urban development. The resulting barrage effect, changes in groundwater levels and directions that are not taken into account at the design stage, can be accompanied by significant deterioration of soil properties and the General stress-strain state at the base of existing buildings and structures. This suggests the need for careful study of the properties of soils at significant depths, the development of forecasts of possible changes of the state of the soil massif and hydrogeological conditions, the implementation of a comprehensive survey of the bases of closely spaced buildings and structures, and significantly larger volume of engineering-geological surveys compared to the current regulations.